Organic thioether or selenoether silver complexes as emulsion sensitizers

ABSTRACT

PHOTOGRAPHIC SILVER BROMOIODIDE EMULSIONS ARE SPECTRALLY SENSITIZED BY ADDING THERETO A MIXTURE COMPRISING A PHOTOGRAPHIC SPECTRAL SENSITIZING DYE AND A COMPLEX OF SILVER WITH AN ORGANIC THIOETHER OR AN ORGANIC SELENOETHER. ADDITION OF THE SILVER COMPLEX REDUCES THE BLUE DESENSITIZATION CAUSED BY THE SENSITIZING DYE AND THUS INCREASES SPECTRAL SENSITIZATION EFFICIENCY, INCUBATION STABILITY OF THE EMULSION IS ALSO ENHANCED.

United States Patent 3,671,260 ORGANIC THIOETHER 0R SELENOETHER SILVERCOMPLEXES AS EMULSION SENSITIZERS Edwin N. Oftedahl, Rochester, ThomasJ. Huttemann,

Jr., Henrietta, and Charles A. Gotle, Brockport, N.Y.,

assignors to Eastman Kodak Company, Rochester, NY. No Drawing. FiledJan. 14, 1971, Ser. No. 106,531

Int. Cl. G03c N28 US. Cl. 96-122 11 Claims ABSTRACT OF THE DISCLOSUREPhotographic silver bromoiodide emulsions are spectrally sensitized byadding thereto a mixture comprising a photographic spectral sensitizingdye and a complex of silver with an organic thioether or an organicselenoether.

Addition of the silver complex reduces the blue desensitization causedby the sensitizing dye and thus increases spectral sensitizationefficiency. Incubation stability of the emulsion is also enhanced.

This invention relates to photographic materials, and more particularlyto a method for spectrally sensitizing photographic silver halideemulsions.

Williams and Cossar in US. Pat. 3,021,215, issued Feb. 13, 1962, incolumn 14, lines 27-33 describe the addition of poly(thiaalkylene diols)to spectrally sensitized gelatin silver bromoiodide emulsions. Suchcompounds increase the speed of photographic silver halide emulsions.Applicants investigation of the use of various complexes in spectrallysensitizing silver halide emulsions indicates that an unrecognizedphenomenon probably occurred when Williams and Cossar addedpoly(thiaalkylene diols) to spectrally sensitized silver bromoiodideemulsions. The poly(thiaalkylene diols) probably formed a complex withsilver present in the silver halide crystals, and the silverpoly(thiaallylene diol) complex possibly functioned to decrease the bluedesensitization normally caused by photographic spectral sensitizingdyes. It would be desirable to provide still further decreases in theamount of gesensitization caused by photographic spectral sensitizingyes.

One object of this invention is to reduce the blue de- (siensitizationcaused by photographic spectral sensitizing yes.

Another object of this invention is to increase the efficiency ofphotographic spectral sensitization.

Still another object of this invention is to enhance the incubationstability of spectrally sensitized photographic silver halide emulsions.

Other objects of this invention will be apparent from this disclosureand the appended claims.

In accordance with this invention, a photographic silver bromoiodideemulsion is spectrally sensitized by adding thereto a mixture comprisinga photographic spectral sensitizing dye and a complex of silver with anorganic thioether or an organic selenoether. Photographic emulsionsspectrally sensitized in accordance with this invention exhibit reducedbluedesensitization caused by the dye. The process of the inventionincreases the efficiency of spectral sensitization, both for molecularand l-band absorption. The invention also enhances the incubationstability of photographic emulsions, particularly those Patented June20, 1972 emulsions sensitized with red and infrared photographicspectral sensitizing dyes.

In accordance with a preferred embodiment of this invention, the mixtureof photographic spectral sensitizing dye and the silver complex areheated prior to incorporation in the silver bromoiodide emulsion. Theheating step results in decreased dye desensitization, increasedspectrally sensitized speeds and reduced fog.

In still another embodiment of this invention, photographic silverbromoiodide emulsions treated with a mixture comprising a photographicspectral sensitizing dye and a complex of silver with an organicthioether or selenoether are hypersensitized. Any of the conventionalprior art hypersensitizing treatments can be utilized, including thosementioned by Mees and James, The Theory of the Photographic Process, 3rdEdition, published by the Macmillan Co., 1966, page 252, and includingbathing the finished coating in Water, an amine such as diethylamine, anammoniacal solution or a solution of a silver salt, such as an aqueoussolution of silver nitrite.

Coated emulsions are advantageously hypersensitized, e.g., by bathing ina dilute ammoniacal solution, such as 2 parts of 28% ammonia dilutedwith parts water for 2 to 3 minutes at about 5 C. Other suitable meansfor hypersensitizing photographic emulsions appear in an article byMiller et al., Journal of the Photographic Society of America, vol. 12,pages 5866l0, No. 10, November 1946.

The term photographic spectral sensitizing dye is used herein and in theappended claims as a word of art which denotes dyes employed as spectralsensitizers in negative, developing-out silver halide emulsions. Suchdyes generally have a polarographic cathodic halfwave potential morepositive than about l.05 volts. In accordance with the presentinvention, cathodic measurements are made with a l 1O molar solution ofthe dye in a solvent, for example, methanol which is 0.05 molar inlithium chloride using a dropping mercury electrode with thepolarographic halfwave potential for the most positive cathodic wavebeing designated E Anodic measurements are made with 1X 10* molaraqueous solvent solution, for example, methanolic solutions of the dyewhich are 0.05 molar in sodium acetate and 0.05 molar in acetic acidusing a carbon paste of pyrolytic graphite electrode, with thevoltametric half peak potential for the most negative anodic responsebeing designated E In each measurement, the reference electrode is anaqueous silver-silver chloride (saturated potassium chloride) electrodeat 20 C. Electrochemical measurements of this type are known in the artand are described in New Instrumental Methods in Electrochemistry, byDelahay, Interscience Publishers, New York, N.Y., 1954; Polarography, byKolthoff and Lingane, 2nd Edition, Interscience Publishers, New York,N.Y., 1952; Analytical Chemistry, 36, 2426 (1964) by Elving; andAnalytical Chemistry, 30, 1576 (1958) by Adams. The less negative (morepositive) the cathodic (reduction) potential, the greater is theelectron affinity of a dye and conversely the less positive (morenegative) the anodic (oxidation) potential of a dye, the greater is itselectron-donating ability.

The useful photographic spectral sensitizing dyes include the methinedyes, such as the cyanine, merocyanine, hemicyanine, oxonol and styryldyes. Typical useful methine dyes are described in Brooker U.S. Pats.1,846,- 301, issued Feb. 23, 1932; 1,846,302, issued Feb. 23,

1932; and 1,942,854, issued Jan. 9, 1934; White US. Pat. 11,990,507,issued Feb. 12, 1935; Brooker and White U .8. Patents 2,112,140, issuedMar. 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued Jan.10, 1950, and 2,739,964, issued Mar. 27, 1956; Brooker and Keyes US.Pat. 2,493,748, issued J an. 10, 1950; Sprague U.S. Pats. 2,503,776,issued Apr. 11, 1950, and 2,519,001, issued Aug. 15, 1950; 'Heseltineand Brooker U.S. Pat. 2,666,761, issued Jan. 19, 1954; Heseltine US.Pat. 2,734,900, issued Feb. 14, 1956; Van Lare US. Pat. 2,739,149,issued Mar. 20, 1956; and Kodak Limited British 'Pat. 450,958, acceptedJuly 15, 1936.

:Preferred cyanine dyes which can be employed in accordance with thisinvention have the following genwherein d and it each represents apositive integer of from 1 to 2, m represents a positive integer of from1 to 5, each L represents a methine group (e.g., CH=, -C(CH etc.), and Zand Z each represents the non-metallic atoms necessary to complete aheterocyclic nucleus containing from to 6 atoms in the heterocyclicring, e.g., thiazole, 4-phenylthiazole, 4,5-diphenylthiazole,4-(2-thienyl)thiazole, 4-methylthiazole, 'benzothiazole, 4-chlorobenzothiazole, 4-methylbenzothiazole, 4-methoxybenzothiazole,4-ethoxybenzothiazole, 4-phenylbenzothiazole, S-chlorobenzothiazole,5-bromobenzothiazole, 5- methylbenzothiazole, S-methoxybenzothiazole,5-ethoxybenzothiazole, S-phenylbenzothiazole, 6-chlorobenzothiazole,6-bromobenzothiazole, 6-methylbenzothiazole, 6- methoxybenzothiazole,'fi-ethoxybenzothiazole, 4-phenyloxazole, benzoxazole, 5chlorobenzoxazole, S-methylbenzoxazole, 5 bromobenzoxazole, 5methoxybenzoxazole, 5-ethoxybenzoxazole, S-phenylbenzoxazole,1,3-dialkyl, 1,3-diaryl or 1-al'kyl-3-ary1, imidazoles andbenzimidazoles, such as 5-chloro-l,3-dial'kyl benzimidazoles,5-chlor0-1,3-diaryl benzimidazoles, 5,6-dichloro -1,3 dialkylbenzimidazoles, 5,6-dichloro 1,3 diaryl benzimidazoles,5-methoxy-1,3-dialkyl benzimidazoles, S-methoxy- 1,3-diarylbenzimidazoles, 5-cyano-1,3-dialkyl benzimidazoles, 5-cyano 1,3 diarylbenzimidazoles, 1,3-dia1kylnaphth[1,2-d]imidazole, 1,3diarylnaphth[2,1-d]imidazole, 4-methylselenazole, 4-phenylselenazole,selenazole, benzoselenazole, 5-chlorobenzoselenazole, a-naphthothiazole,fl-naphthothiazole, quinoline, G-methylquinoline, 6- methoxyquinoline,6-ethoxyquinoline, 6-chloroquinoline, 4 methoxyquinoline, 4ethoxyquinoline, 4-methylquinoline, 8-methoxyquinoline,fi-methylquinoline, 4-chloroquinoline, 3,3-dimethylindolenine, etc.; Xrepresents an acid anion, such as chloride, bromide, p-toluenesulfonate, methane sulfonate, methylsulfate, ethylsulfate, perchlorate,etc.; R and R each represents an alkyl group (including substitutedalkyl) having from 1 to 118, and preferably 1 to 4 carbon atoms, such asmethyl, ethyl, propyl, isopropyl, butyl, sec-butyl, hexyl, dodecyl,octadecyl, benzyl, p-phenylethyl sulfoalkyl such as S-sulfoethyl,'ysulfopropyl, -sulfobutyl, a-sulfobutyl, etc.; carboxyalkyl such asB-carboxyethyl, 'y-carboxypropyl, 6-carboxybutyl, etc.; sulfatoalkylsuch as 'y-sulfatopropyl and fi-sulfatobutyl, etc., or an alkylene chainwhich joins with a methine linkage, such as a butylene or neopentylenelinkage, or an aryl group such as phenyl, naphthyl, tolyl,pchlorophenyl, etc. It will be noted that in some instances, the acidanion, represented by X in the above formula, is included in thesubstituent represented by R such as dyes containing the betaine typestructure. Some specific useful cyanine dyes are listed below:

'1',3-diethylthia-2'-cyanine chloride 1,l'-diethyl-2,'2'-cyaninechloride 3,3'-diethy1oxacarbocyanine iodide5,5-dichloro-3,3'-diethylthiacarbocyanine iodidel,1'-diethyl-2,2'-carbocyanine iodide 3,3'-diethylthiazolocarbocyanineiodide 3,3'-diethyl-4,4'-dephenylthiazolocarbocyanine iodide3,3'-diethyl-9-methylthiacarbocyanine iodide 1,3,3-triethylbenzimidazole-oxacarbocyanine iodide5-chloro-l,3,3-triethylbenzimidaZolo-oxacarbocyanine iodide5,6-dichloro-1,3,3'-triethylbenzimidazolothiacarbocyanine iodidel,1'-3-triethylbenzimidaZol0-2-carbocyanine iodide1,1',3-triethylbenzimidazolo-4'-carbocyanine iodide1,1'-diethyl-2,4-carbocyanine iodide1,3-diethyl-4-methylthiazo1o-2-carbocyanine iodide3,3-diethylthiadicarbocyanine iodide 1, 1 '-diethyl-2,2-dicarbocyanineiodide 1',3-diethylthia-2'-dicarbocyanine iodideAnhydro-5,5'-6,6-te-trachloro-1,1,3-triethy1-3'-(4-su1fobutyl)benzimidazolocarbocyaninehydroxide Anhydro-5,6-dichloro-1-ethy1-3-(3-sulfobutyl)-3'-(3-sulfopropyl)-4',5'-benzobenzimidazolothiacarboy cyanine hydroxide1,1',3,3 -tetraethyl-naphth[1,2-d]imidazolocarbocyanine iodideAnhydro-5,'6-dichloro-1,3-diethyl-(3-sulfobutyl)-benzimidazoloselenacarbocyaninehydroxide 1,2-diethylthia-4-carbocyanine iodideAnhydro-5,5',6,6'-tetrachloro-1,1'-diethy1-3,3'-di(4-sulfobutyl)-benzimidazolocarbocyanine hydroxide Merocyanine dyesespecially useful in this invention have the following formula:

,-Q-, R,-I 'I -0H=0H)i-lo= LL)k-1=o-o=o wherein L represents a methinegroup, such as those mentioned above; Z is selected from a value givenfor Z and Z above; R is an alkyl or aryl group, such as those referredto above; 1' and k each represents a positive integer of from 1 to 2;and Q represents the non-metallic atoms necessary to complete aheterocyclic ketomethylene nucleus of the type used in merocyanine dyestypically containing hetero atoms selected from nitrogen, sulfur,selenium and oxygen, such as a 1,3-dioxane-4,6-dione nucleus, e.g.,2,2-dialkyl-1,3-dioxane-4,6-dione, etc.; a 2-pyrazolin-5-one nucleus;e.g., 3-methyl-1-phenyl-2- pyrazolin-S-one, 1-phenyl-2-pyrazolin-5-one,1-(2-benzothiazolyl)-3-methyl-2-pyrazolin-5-one, etc.; an isoxazolonenucleus, e.g., 3-phenyl 5 (4H)-isoxazolone, 3-methyl- 5(4H)-isoxazolone,etc.; an oxindole nucleus, e.g., l-alkyl- 2-oxindoles, etc.; a2,4,6-triketohexahydropyrimidine nucleus, e.g., barbituric acid or2-thiobarbituric acid as well as their l-alkyl (e.g., l-methyl, l-ethyl,l-propyl, l-heptyl, etc.) or 1,3-dialkyl (e.g., 1,3-dimethyl,1,3-diethyl, 1,3- dipropyl, 1,3 diisopropyl, 1,3 dicyclohexyl, 1,3di(flmethoxyethyl), etc.; or 1,3-diaryl (e.g., 1,3-diphenyl, 1,3- di(pchlorophenyl), 1,3 di(p ethoxycarbonylphenyl), etc.); or l-aryl (e.g.,l-phenyl, l-p-chlorophenyl, l-pethoxycarbonylphenyl), etc.) or1-alkyl-3-aryl (e.g., 1-ethy1-3-phenyl, 1-n-heptyl-3-phenyl, etc.)derivatives, 21 rhodanine nucleus (i.e., 2 thio 2,4 thiazolidinedioneseries), such as rhodanine, 3-alkylrhodanines, e.g., 3-ethylrhodanine,3-ally1rhodanine, etc., S-carboxyalkylrhodanines, e.g.,3-(2-carboxyethyl)rhodanine, 3-(4-carboxybutyl)rhodanine, etc.,3-sulfoa1kylrhodanines, e.g., 3-(2- sulfoethyl)rhodanine,3-(3-sulfopropyl)rhodanine, 3-(4- sulfobutyl)rhodanine, etc., or3-arylrhodanines, e.g., 3-phenylrhodanine, etc., a2-(3H)-imidazo[1,2-a]pyridone nucleus; a5,7-dioxo-6,7-dihydro-5-thiazolo[3,2-a]pyrimidine nucleus, e.g.,5,7-dioxo-3-phenyl-6,7-dihydro-5-thiazolo[3,2-a]pyrimidine, etc.; a2-thio-2,4-oxazolidinedione nucleus (i.e., those of the2-thio-2,4(3H,5H)-oxazoledione series) e.g.,3-ethyl-2-thio-2,4-oxazolidinedione, 3-(2-su1foethyl)-2-thio 2,4oxazolidinedione, 3-(4-sulfobutyl)-2-thio-2,4-oxazolidinedione, 3(3carboxypropyl)- 2-thio-2,4-oxazolidinedione, etc.; a thianaphthenonenucleus, e.g., 3-(2H)-thianaphthenone, etc.; a 2-thio-2,5-

thiazolidinedione nucleus (i.e., the 2-thio-2,5-(3H,4H)- thiazoledioneseries), e.g., 3-ethyl-2-thio-2,5-thiazolidinedione, etc.; a2,4-thiazolidinedione nucleus, e.g., 2,4- thiazolidinedione,3-ethyl-2,4-thiazolidinedione, 3-phenyl- 2,4 thiazolidinedione,3-a-naphthyl-2,4-thiazolidinedione, etc.; a thiazolidinone nucleus,e.g., 4-thiazolidinone, 3-ethyl-4-thiazolidinone,3-phenyl-4-thiazolidinone, 3-0:- naphthyl-4-thiazolidinone, etc.; a2-thiazolin-4-one nucleus, e.g., 2-ethylmercapto-2-thiazolin-4-one,2-alky1- phenylamino-Z-thiazolin 4 one,2-diphenylamino-2-thiazolin-4-one, etc.; a 2-imino-4-oxazolidinone(i.e., pseudohydantoin) nucleus; 21 2,4-imidazolidinedione (hydantoin)nucleus, e.g., 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione,3-phenyl-2,4-imidazolidinedione, 3-u-naphthyl- 2,4-imidazolidinedione,l,3-diethyl-2,4-imidazolidinedione, l-ethyl 3 phenyl 2,4imidazolidinedione, l-ethyl-3-anaphthyl-2,4-imidazolidinedione,1,3-diphenyl 2,4 imidazolidinedione, etc.; a2-thio-2,4-imidazolidinedione (i.e., 2-thiohydantoin) nucleus, e.g.,2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidinedione,3-(4-sulfobutyl)-2-thio-2,4-imidazolidinedione, 3-(2-carboxyethyl)-2-thio-2,4-imidazolidinedione, 3-phenyl 2 thio-2,4-imidazolidinedione, 3a naphthyl 2 thio-2,4-imidazolidine dione,1,3-diethyl-2-thio-2,4-imidazolidinedione, l-ethyl-3-phenyl-2-thio2,4-imidazolidinedione, 1 ethyl-3-a-naphthyl-2-thio 2,4imidazolidinedione, 1,3-diphenyl-2-thio- 2,4-imidazolidinedione, etc.; aZ-imidazolin-S-one nucleus, e.g., 2-propylmercapto-Z-imidazolin-S-one,etc. Preferably, Q and Q each represents the atoms to complete a ringcontaining from 3 to 4 carbon atoms, one nitrogen atom and one atomselected from the group consisting of nitrogen, oxygen, sulfur andselenium. Typical useful merocyanine dyes are described, for example, inBrooker et al. Pats. 2,493,747 and 2,493,748, both issued Jan. 10, l 0.

Particularly good results are obtained with the following cyanine andmerocyanine dyes:

3,3'-diethyl-9, l 1,15,17-dineopentylenethiapentacarbocyanine iodide3,3'-diethylselenadicarbocyanine iodide 1,3-diethyl-5- [4-(3-ethyl-2-benzothiazolinylidene -2- butenylidene]-2-thiobarbituric acid3,3'-diethylthiacarbocyanine chloride 3,3'-diethylcyanine chloride3,3-diethylcarbocyanine iodide5,5',6,6'-tetrachloro-1,1',3,3-tetraethylbenzimidazolocarbocyaninechlorideAnhydro-5,5,6,6'-tetrachloro-1,1-diethyl-3,3'-di(3-sulfobutyl)benzimidazolocarbocyaninehydroxide Anhydro-S,5,6,6'-tetrachloro-1,l,3-triethyl3-(3-sulfobutyl)benzimidazolocarbocyanine hydroxide5,5'-dichloro-3,3-diethyl-9-phenylselenacarbocyanine iodide3,3,9-triethyl-5,6,5',6'-dibenzothiacarbocyanine p-toluenesulfonate Ifdesired, combinations of photographic spectral sensitizing dyes can beemployed in the practice of the invention.

Any silver complex with an organic thioether compound or an organicselenoether compound can be utilized in the practice of this invention.A preferred class of complexes are those of silver with an alkane orcycloalkane containing from 5 to 30 carbon atoms in which from 2 to 6-'CH groups, but not more than one half of the total number of CHgroups, are replaced with a divalent selenium or, preferably, a divalentsulfur atom. Dithia-tetraoxacyclooctadecanes are especially usefulsilver complexing agents. Some organic thioether and selenoethercompounds which form particularly useful silver complexes are set outbelow:

l,4-bis( 5-hydroxy-3-thiapentyl) piperazine3,4-diaza-1,16-dithia-9,12,l5-trioxa-2,4cycloheptadecadiene-2,5-sulfide.

Poly [2,2-thiodiethylsuccinate]l,l0-dithia-4,7,13,16-tetraoxacyclooctadecane4,7,13,16-tetraoxa-l,lO-diselenocyclooctadecane Poly[thiodiethyleneglutarate] 1,3-bis(4-phenyl-1,2,4-triazol-3-ylthio) propane1,8-dihydroxy-3,6-d-ithiaoctane Bis(3-oxapentamethylenecarbamyloxyethyldisulfide) The complex of silver with the organicthioether or selenoether can be prepared in any convenient manner priorto incorporation in the emulsion. Advantageously, the complexing agentis mixed with a suitable source, such as silver nitrate in a commonsolvent. The mixture of sensitizing dye and silver complexing agent canbe formulated in any convenient manner. For example, a silver source,such as silver nitrate, can be added to a solution containing theorganic thioether or selenoether complexing agent and dye. The solventis not critical; any solvent is useful which dissolves the dye, silversource, complexing agent and the silver complex formed. Methanol is asolvent for many photographic sensitizing dyes and provides goodresults. Other typical useful solvents include ethanol, isopropanol,pyridine, etc.

Preferably the mixture of dye and silver-organic thioether orselenoether complex is heated just prior to incorporation in theemulsion. Heating a solution of dye and silver-organic complex totemperatures of about 30 to C., and preferably about 40 to 60 C., andmaintaining the solution at that temperature from about 2 minutes to onehour, and preferably about 5 to 10 minutes, provides excellent increasesin the spectrally sensitized speed of emulsions sensitized.

The photographic spectral sensitizing dye is incorporated in theemulsions in concentrations suflicient to spectrally sensitize theemulsion. Typical dyes function as efficient spectral sensitizers inconcentrations of from about .001 to about .300 gram per mole of silverin the emulsion.

The silver-organic complex is incorporated in the emulsions inconcentrations sufficient to decrease the blue desensitization caused bythe photographic sensitizing dye, and to increase the eflic'iency ofspectral sensitization by the dye. Amounts of about 0.25 to about 0.75gram of silver complex per mole of silver halide in the emulsionsprovide satisfactory results.

The process of the invention is useful in spectrally sensitizingphotographic silver bromoiodide emulsions. The halide of such emulsionspreferably contains .at least 60%, and preferably at least 80 tobromide. Other photographic silver halides, such as silverchlorobromide, are ripened (i.e., the grains grow larger) by thecomplexing agents employed herein.

Emulsions sensitized as described herein can be coated on any suitablephotographic support, such as glass, film base such as celluloseacetate, cellulose acetate butyrate, polyesters such as poly(ethyleneterephthalate), paper, baryta coated paper, polyolefin coated paper,e.g., polyethylene or polypropylene coated paper, which may be electronbombarded to promote emulsion adhesion, to produce the novelphotographic elements of the invention.

Emulsions sensitized in accordance with this invention can containaddenda such as chemical sensitizers, e.g., sulfur sensitizers (e.g.,allyl thiocarbamate, thiourea, allylisothiocyanate, cystine, etc.)various gold compounds (e.g., potassium chloroaurate, auric trichloride,etc. (see Baldsiefen US. Pat. 2,540,085, issued Feb. 6, 1951;Damschroder US Pat. 2,597,856, issued May 27, 1952 and Yutzy et al. US.Pat. 2,597,915, issued May 27, 1952), various palladium compounds suchas palladium chloride (Baldsiefen US. Patent 2,540,086, issued Feb. 6,1951), potassium chloropalladate (Stauffer et al. U.S. Patent 2,598,079,issued May 27, 1952), etc., or mixtures of such sensitizers;antifoggants such as ammonium chloroplatinate (Trivelli et al. US.Patent 2,- 566,245, issued Aug. 28, 1951), ammonium chloroplatinate(Trivelli et al. US. Patent 2,566,263, issued Aug.

28, 1951), benzotriazole, nitrobenzimidazole, S-nitroimidazole,benzidine, mercaptans, etc. (see Mees and James, The Theory of thePhotographic Process, Macmillan Publishers, 1942, page 460), or mixturesthereof. The silver halide emulsions of the invention can be hardenedwith any suitable hardener, including aldehyde hardeners such asformaldehyde, and mucochloric acid, aziridine hardeners, hardeners whichare derivatives of dioxane, oxypolysaccharides such as oxy starch or oxyplant gums, and the like. The emulsion layers can also containadditional additives, particularly those known to be beneficial inphotographic emulsions, including, for example, lubricating materials,stabilizers, speed-increasing materials, absorbing dyes, plasticizers,and the like. These photographic emulsions can also contain additionalspectral sensitizing dyes. Furthermore, these emulsions can containcolor-forming couplers or can be developed in solutions containingcouplers or other colorgenerating materials. Among the useful colorformers are the monomeric and polymeric color formers, e.g., pyrazolonecolor formers, as well as phenolic, heterocyclic and open-chain couplershaving a reactive methylene group. The color-forming couplers can beincorporated into the photographic silver halide emulsion using anysuitable technique, e.g., techniques of the type shown in Jelley et al.US. Pat. 2,322,027, issued June 15, 1943, Fierke et al. US. Pat.2,801,171, issued July 30, 1957, Fisher U.S. Pats. 1,055,155 and1,102,028, issued Mar. 4, 1913 and June 30, 1914, respectively, andWilmanns US. Pat. 2,186,849, issued Jan. 9, 1949. They can also bedeveloped using incorporated developers such as polyhydroxybenzenes,aminophenols, 3-pyrazolidones, and the like.

The following examples are included for a further understanding of thisinvention.

EXAMPLE 1 A sulfur and gold sensitized, large grain, liquid gelatinsilver bromoiodide (about 6 mole percent of the halide being iodide)emulsion is stirred thoroughly, combined with a suitable surfactant(e.g., saponin) and hardener (e.g., formaldehyde) and coated on acellulose acetate support at a coverage of 350 mg. silver and 810 mg.gelatin per square foot. One set of coatings is exposed to tungstenlight on an Eastman 1B sensitometer and processed for minutes at 20 C.in Kodak D-SO developer. The relative speed values obtained are given inTable I. The relative blue speed is obtained by exposing the elementthrough a combination of filters: Wratten 35 plus 38A plus a blue filterthat absorbs green and red light and transmits blue light.

EXAMPLE 2 The procedure of Example 1 is followed except that infraredsensitizing dyes I and II (identified at the end of Table I) are addedto the emulsion along with the silver complexing agent 1,10-dithio4,7,13,16 tetraoxacyclooctadecane (which forms a silver complex withsilver ion in the emulsion). The infrared speed is determined byexposure on the sensitometer through a Wratten 89B filter. The resultsappear in Table I.

EXAMPLES 3-5 The procedure of Example 2 is repeated except that thecomplexing agent and sensitizing dyes I and II are dissolved in methanolwith varying amounts of silver nitrate and the mixture obtained is addedto the emulsion. The results appear in Table I.

EXAMPLES 6-8 The procedure of Examples 3-5 is repeated except that themethanolic solution of sensitizing dyes, silver complexing agent andsilver nitrate is heated to 50 C., held at that temperature for 6minutes, and then added to the emulsion. The results are shown in TableI.

TABLE I Com- Mg. Relative Relative plexing AgNO; blue infrared agentmole Ag speed speed min.

1 331 06 D 100 06 D 1 120 115 06 D 1 240 138 145 06 D 1 480 151 182 10 D2 120 04 D 2 240 115 138 06 D 2 480 159 209 06 1 chemicals pre-mixed inmethyl alcohol, then added to the em 1011.

2 All chemicals pre-mixed in methyl alcohol, heated to 50 0., held 6min., and then added to the emulsion.

Dye II: D: 1,10

The data in Table I shows that the ex situ preparation of the silvercomplex-dye mixture is more efiicient than the in situ formation of thesilver complex of the organic ligand, D (Example 2 versus Examples 3-8).Examples 3-5 and 6-8 indicate that the amount of silver nitrateavailable to form the silver complex has a marked influence on theefiiciency of the supersensitization. In addition, a heat treatmentduring the pre-mixing step causes a further gain in spectrallysensitized speed. It is believed that the ex situ mixing of silvernitrate, organic ligand and sensitizing dye alone or with a heattreatment, facilitates the formation of the silver complex which in turnacts as a more efficient supersensitizer for the sensitizing dyecombination (Dye I and Dye II). Note that the heat treatment stepprevents the undue formation of fog (Example 5 versus 8). The ex situpreparation of the silver-organic complex, and the pre-mixing of thesensitizing dye and the silver-organic complex, produces increased blue(intrinsic) sensitivity, higher spectral sensitivity and reduced minimumdensities. Results generally similar to those in Table I are obtainedwhen other spectral sensitizing dyes, such as those mentioned above, andwhen other organic thioether or selenoether complexing agents, are usedin place of Dyes I and II and Complexing Agent D. Dyes which spectrallysensitize to shorter wavelengths than infrared are useful in theinvention, and are supersensitized in the general region in which theyspectrally sensitize.

EXAMPLE 9 A non-spectrally sensitized control coating is prepared andcoated as in Example 1. The dried element is exposed and processed as inExamples 1-8, except that a Wratten 29 filter (red) is substituted forthe Wratten 89B filter. An additional set of coatings is hypersensitizedby bathing for 2 to 3 minutes in a 5 C. solution consisting of 2 parts28% aqueous ammoniacal solution and 100 parts water, rinsed in methanol,dried, immediately exposed and processed as the control coating. Theunhypered coating is assigned a blue speed of 100 and has a minimumdensity of 0.04. The ammonia hypered coating has a relative blue speedof 138 and a minimum density of 0.06.

EXAMPLES 10-23 The procedure set out in Example 9 is followed with theexception that the emulsion is spectrally sensitized with a pre-mixed,pre-heated solution consisting of a spectral sensitizing dye (at variouslevels), and 0.6 gram of silver complex per silver mole of emulsion. Thesilver complexing agent (D) is identical to the one used in Examples2-8. The sensitometric data obtained from these unhypered and hyperedcoatings are listed in Table II. The following individual sensitizingdyes are incorporated in the coatings:

(HI) 5,5'-dichloro-3,3'-diethyl-9-phenylselenacarbocyanine iodide 9 (IV)3,3'-9 triethyl-5,6,5',6'-dibenzothiacarbocyanine p-toluenesulfonate (V)5,5-dichloro-3,3,9-triethylthiacarbocyanine bromide (VI)3,3'-dimethyl-9-phenylthiacarbocyanine iodide 10 The invention has beendescribed in detail with particular reference to preferred embodimentsthereof, but it will be understood that variations and modifications canbe effected within the spirit and scope of the invention describedhereinabove and in the appended claims.

TABLE II F: Unhypered Ammonia hypered Format Relative Relative RelativeRelative Dye at mgJmole silver :1: blue red blue red Example complex at0.6 g./mole silver speed speed Dmin speed speed Dmin 9 None- 100 .04 138.06 10.... 83 105 .00 120 417 .08 11 53 110 .08 91 525 .10 12--- 120 39s.06 120 692 .08 13... 110 525 .08 115 795 .10 14. 95 159 .00 105 302 1s87 219 10 91 380 14 16. 105 219 0s 95 251 10 11- 110 380 .12 83 363 .1418. 100 219 .06 105 417 .08 19..- g y 80 251 .10 73 39s .12 150 mg. dyeV plus complex 115 316 06 95 363 08 21 300 mg. dye V Iplus complex"..-100 380 14 80 417 14 22 250 mg;dyeV 42 21 .10 4e 83 .10 23 250 mg. dyeVI plus complex.... 76 55 10 73 132 12 A study of the data in Table IIreveals that unhypered We claim: coatings, containing both the dye andthe silver complex, 1. The method of spectrally sensitizing aphotographic show equal or nearly equal red speeds in comparison with 25silver bromoiodide emulsion which comprises adding to the hypered coatngs containmg an equal amount of sensaid emulsion a mixture comprising aphotographic specsitizing dye anclno silver complex. For instance,compare tral sensitizing dye and a complex of silver with an or- Example13 (unhypered) with Example 11 (hypered), ganic thioether or an organicselenoether. Example 17 (unhypered) with Example 15 (hypered), 2. Themethod of spectrally sensitizing a photographic Example 21 (unhypered)with Example 19 (hypered) and silver bromoiodide emulsion whichcomprises adding to Example 23 (u yp Wlth f p 22 yp fimsaidemulsionamixture comprising: in most cases the yp cotmgs l In (a) aphotographic spectral sensitizing dye having one some examples thehypered coatings contammg a silver f h following formulas; complexingagent have more speed than hypered coatings containing a. sensitizingdye and no complexing agent. For we 9 example, compare the hyperedcoatings of Examples 10 x and 11 (no complex) with Examples 12 and 13(comand plex). Z Q

2 2 a 2 r a EXAMPLES 4-3 40 R3N(-CH=CH) 1o=(L-L)k 1=o o=o Mees and Jamesin The Theory of the Photographic Process 3rd Edition published by theMacmillan C0 wherein Z, Z and Z each represents the non-metallic NewYork, 1966, state at page 258, that dye desensitizaatoms: Peqmred toComplete heterocychc l l tion increases with increasing pAg. However,lowering the contammg from 5 to 6 the h'eterocychc nng; pAg of a coatingcauses a loss in storage stability and each L represents a methmelmkage, R2 and R3 an increase in fog. These examples demonstrate thatthe F 9 represents alkyl g p an alkylene group use of a silvercomplexing agent with a spectral sensitizing Joined to a methmellnkfige. an Y p; Q dye duplicates the sensitometric advanges of low pAgrepresents the Rolf-Install atoms l'equlred to coatings with the dyealone, without an increase in fog- Plate a hetefocycllc ketofnethylene1111016138 9 ging propensity upon incubation. The emulsion, coating mgfrom 5 to 6 atoms 1n the heterocyclic rmg; m format, exposure andprocessing procedures are the same represents an nteger of from 1 to 5d, n and 1' each as in Examples 9-23. The final pAg of the finalemulsion represents an integer of from 1 to 2; k represents ancomposition is adjusted with a solution of silver nitrate. integer offrom 1 to 3; and X represents an acid Table III contains thesensitometric data obtained from anion; and these examples. Thecomplexing agent is 1,10-dithia-4,7, (b) a complex of silver w1th analkane or cycloalkane 13,16-tetraoxacyclooctadecane (D).

containing from 5 to 20 carbon atoms in which from TABLE III 160 m d emole 1 wk. 120 F.

Ag dz con i piex at Relative Relative 50% RH. Example 0.6 g./mole Ag pAgblue speed red speed Fog incubation fog 24 None control 8. 2 100 06 0425-.- Dye 8. 2 40 87 06 06 26--. Dye III plus complex 8. 2 67 263 .06 0627- None (control) 7. 8 110 04 05 28. Dye III 7. 8 58 132 08 06 29. DyeIII plus complex. 7. 8 73 302 07 07 30. None (control) 7.4 63 .36 .5231. Dye III 7.4 95 276 .16 .15 32 Dye III plus complex- 7. 4 69 316 1420 Norm-Dye III:

55-d1ehlore-3,3-diethyl-Q-phenylselenaearbocyanine iodide. OomplexingAgent D: 1,10-dithia4,7,13,1otetraoxacyclooctadecane. Exposure: 1/5second 500W 5,400 K. Processing: 5 minutes Kodak D-50 developer.

2 to 6 CH groups, but not more than one half the total number of CH:groups, are replaced with a divalent sulfur or selenium atom. 3. Theprocess of claim 2 wherein said complex of silver is asilver-dithia-tetraoxacyclooctadecane complex.

4. The metod of spectrally sensitizing a photographic silver bromoiodideemulsion which comprises adding to 11 said emulsion a methanolicsolution comprising the photographic spectral sensitizing dyes3,3'-diethylselenodicarbocyanine salt andanhydro-1-ethyl-3-(3-sulfobutyl)thia- 2'-cyanine salt, and a complex ofsilver with 1,10-dithia- 4,7,13,16-tetraoxacyclooctadecane.

5. The method of spectrally sensitizing a photographic silverbromoiodide emulsion which comprises heating a solution of a silversalt, an organic thioether or an organic selenoether, and a photographicspectral sensitizing dye; and, adding said heated solution to saidsilver bromoiodide emulsion.

6. The method of spectrally sensitizing a photographic silverbromoiodide emulsion which comprises heating for about 2 minutes to onehour, at about 30 to 80 C., a solution comprising:

(a) a photographic spectral sensitizing dye having one of the followingformulas:

R l I(L=L)d1b=L(L=L)m-1dLL=)n =1 R x and I "Z2 I R II(GH==CH)i-1b=(LL)k-i==0 wherein Z, Z and Z each represents thenon-metallic atoms required to complete a heterocyclic nucleuscontaining from 5 to 6 atoms in the heterocyclic ring; each L representsa methine linkage; R R and R each represents an alkyl group, an alkylenegroup joined to a methine linkage, or an aryl group; Q represents thenon-metallic atoms required to complete a heterocyclic ketomethylenenucleus containing from 5 to 6 atoms in the heterocyclic ring; mrepresents an integer of from 1 to 5; d n and j each represents aninteger of from 1 to 2; k represents an integer of from 1 to 3; and, Xrepresents an acid anion;

(b) a complex of silver with an alkane or cycloalkane containing from 5to 20 carbon atoms in which from 2 to 6 -CH groups, but not more thanone half the total number of CH- groups, are replaced with a divalentsulfur or selenium atom; and adding said heated solution to saidemulsion.

7. The method of claim 6 wherein said heat treatment is conducted forabout 5 to 10 minutes at a temperature of between 40 and 60 C.

8. The method of spectrally sensitizing a photographic silverbromoiodide emulsion which comprises heating for 5 to 10 minutes, at 40to 60 C. a methanolic solution containing the sensitizing dyes3,3'-diethylselenodicarbocyanine salt andanhydro-1-ethyl-3-(3-sulfobutyl)thia-2'- cyanine salt and, a complex ofsilver with 1,10-dithia-4,7, 13,16-tetraoxacyclooctadecane; and, addingsaid heated solution to said emulsion.

9. The process of sensitizing a photographic silver bromoiodide emulsionwhich comprises adding to said emulsion a mixture comprising aphotographic spectral sensitizing dye and a complex of silver with anorganic thioether or selenoether; coating said emulsion on a support;and, bathing said coated emulsion in a hypersensitizing bath.

10. The process of sensitizing a photographic silver bromoiodideemulsion which comprises adding to said emulsion a mixture comprising:

(a) a photographic spectral sensitizing dye having one of the followingformulas;

wherein Z, Z and Z each represents the non-metallic atoms required tocomplete a heterocyclic nucleus containing from 5 to 6 atoms in theheterocyclic ring; each L represents a methine linkage; R R and R eachrepresents an alkyl group, an alkylene group joined to a methinelinkage, or an aryl group; Q represents the non-metallic atoms requiredto complete a heterocyclic ketomethylene nucleus containing from 5 to 6atoms in the heterocyclic ring; In represents an integer of from 1 to 5;d, n and j each represents an integer of from 1 to 2; k represents aninteger of from 1 to 3; and, X represents an acid anion; and v p (b) acomplex of silver with an alkane or cycloalkane containing from 5 to 20carbon atoms in which from 2 to 6 -CH groups, but not more than one halfthe total number of -CH-,-- groups, are replaced with a divalent sulfuror selenium atom; coating said emulsion on a support; and, bathing saidemulsion in an aqueous ammoniacal hypersensitizing bath. 11. The methodof spectrally sensitizing a photographic silver bromoiodide emulsionwhich comprises heating for 5 to 10 minutes, at 40 to 60 C. a methanolicsolution containing the sensitizing dyes3,3'-diethylselenodicarbocyanine salt; anhydro 1ethyl-3-(3-sulfobutyl)thia-2'- cyanine salt and, a complex of silverwith 1,10-dithia-4,7, 13,16-tetraoxacyclooctadecane; coating saidemulsion on a support; and, bathing said emulsion for 2 to 3 minutes inanamrnoniacal bath consisting essentially of 2 parts of 28% aqueousammoniacal solution and parts water, said bath being maintained at about5 C. during hypersensitization.

References Cited UNITED STATES PATENTS 3,598,590 8/1971 Hiickstadt eta1. -2 96-107 3,536,492 10/1970 Luchs 96-110 3,057,724 10/1962 Lovett eta1 96-107 3,046,135 7/1962 Beavers 96-107 3,046,134 7/1962 Dann et al.96-107 3,046,133 7/1962 Minsk 96-107 3,046,129 7/1962 Graham et al.96-107 FOREIGN PATENTS 1,209,813 10/ 1970 Great Britain 96-109 OTHERREFERENCES Beavers, Def. Pub. of Ser. No. 825,420, filed May 16, 1969,published 866 O6 703, Sept. 16, 1969.

NORMAN G. TORCHIN, Primary Examiner J. WINKELMAN, Assistant ExaminerU.S. c1. X.R.

